[amsat-bb] Re: Etching a KLM RHCP/LHCP PCB

i8cvs domenico.i8cvs at tin.it
Mon Nov 7 17:51:31 PST 2011

----- Original Message ----- 
From: "WILLIAMS MICHAEL" <k9qho6762 at sbcglobal.net>
To: <amsat-bb at amsat.org>
Sent: Tuesday, November 08, 2011 12:08 AM
Subject: [amsat-bb] Etching a KLM RHCP/LHCP PCB

Hi Mike, K9QHO

> I've completed and etched one side#1 of the PCB with Press and Peel.


> Side#2 needs to be etched. the artwork is very basic and can be completed
> by hand and Rub-On Etch Resist. I had to drill 8 alignment holes to help
> line up the artwork to each side.

OK, but remember that you have to drill 9 alignment holes only to solder
the relay and that all holes on PCB must be inside metallized.

> Question #1:
>  I don't want the etching solution to leach through the holes. I had some
> donuts to cover the holes, but they are so old that the glue is no good.
> Is there anything that can temporarily fill or cover the holes until side
> #2 is completed?

Mike, I would temporarily fill the holes using a two component epoxy
adesive that become very hard when it dry so that the etching solution
cannot leach through the holes.
A suitable two component epoxy adesive is called UHU-PLUS


As soon side #1 and #2 are etched by the acid soluction it is necessary
to drill again the holes to remove the epoxy adesive but remember that
all 9 holes must be metallized inside so that you must fit a hollow rivet
into each hole and than solder it to both side #1 and #2 of PCB
The holes metallization is very important because othervise you cannot
properly solder the relay pins on both sides of the PCB
When soldering the relay pins do not use too much heat with a high 
power soldering iron because the relay pins are not copper but steel 
that becames immediately oxidated at high temperature.
> Question #2:
>  Has anyone used clear packing tape to cover the areas where the copper
>  is to be protected or will the etching solution just eat it up with the
>  copper?

In my opinion the etching solution just will eat it up with the  copper.

> You have to admit this isn't a typical AMSAT-BB question. In projects
> before this, I just used side #2 as the ground plane.

In my opinion you have place good usefull questions to AMSAT-BB

Don't forget that you must protect the PCB and relay from the water so
that in a separate email I have sent to you a set of pictures to show you 
how I have solved the problem,  

> 73,
> Mike (K9QHO)
73" de

i8CVS Domenico

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